We’ll admit it; there are tons of acronyms in the backup software industry. Sometimes it’s hard to keep up with the entire lingo, like RPO, CSV, or VHD.

If you’re finding yourself scratching your head at terms like these, or just looking for a refresher, read on. This guide is for you.

RTO: Recovery Time Objective. This is how long a business can go without having its data restored without incurring unacceptable losses from a break in business continuity. To use an example, a business might have an RTO of three hours, which is the maximum time they can go without their systems. A business with an RTO needs a backup plan and software that can meet this need in case a disaster occurs.

RPO: Recovery Point Objective. Measured in time, this is the maximum loss of data that a business can occur due to a major incident occurring. E.g. A business might have an RPO of four hours, which means they can lose four hours of data at most. This means daily backups will not be sufficient for their needs.

VMM / Hypervisor: A piece of computer software, firmware, or hardware that creates and runs Virtual Machines.

CSV: Cluster Shared Volumes. These are a feature of failover clustering first introduced in Windows Server 2008 R2 for use with the Hyper-V role. It is a shared disk containing an NTFS or ReFS volume that is made accessible for read and write operations by all nodes within a Windows Server Failover Cluster. This enables Virtual Machines (VM) complete mobility through the cluster as any node can access the VHD files on the shared volume.

VHD: Virtual Hard Disk. A File-format which represents a virtual Hard Disk Drive (HDD). A VHD allows multiple operating systems to reside on a single host machine, as a VHD can contain disk partitions and a file system like a physical HDD.

NTFS: New Technology File System. A Proprietary filing system developed by Microsoft. An improved version of FAT and HPFS. It has improved support for metadata, and allows the use of advanced data structures to improve performance, reliability, and disk space utilization, security access control lists, and file system journaling.

ReFS: Resilient File System. A Microsoft proprietary filing system introduced with Windows Server 2012, with the intent of becoming the “next gen” file system after NTFS.

Bare-Metal Recovery: This is the recovery of a crashed system from ‘bare metal’, or just the hardware. This includes the replacement of all software and data including the operating system and drivers. Bare-metal recovery is for the worst case scenario, usually when all digital data is corrupted and lost.

Type-1 or ‘Native’ Hypervisor: A hypervisor that runs directly on the host’s hardware to control the hardware and to manage guest operating systems. Examples are Microsoft’s Hyper-V, VMware’s ESX/ESXi, the Citrix Xenserver, and Oracle VM Server for SPARC or x86.

Type-2 or ‘Hosted’ Hypervisor: A hypervisor that runs on a conventional operating system just like other computer programs do. Examples are VMware, Workstation, VMware Player, VirtualBox, and QEMU.

Failover Clustering / High-availability Clusters: A group of computers that support server applications that can be reliably used with minimum downtime. These use high availability software to harness redundant computers in clusters that provide continued service when components fail.

High Availability Software: The use of software that ensures systems are running and available most of the time. Most systems attempt to achieve ‘five-nines’ availability (99.999%). A High Availability Software is determined by its performance when subsystems fail, its ability to resume service in a state close to when the original failure took place, and its ability to perform other service-affecting task (E.g. Software upgrade or configuration changes) in a manner that eliminates or minimize down time.


So when someone next tells you BackupAssist does bare-metal and Hyper-V recoveries fast enough to meet your RPOs and RTOs, you’ll know exactly what they’re talking about.

Posted by Adam Ipsen

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